Update Azure.Identity to 1.15.0 (#224)

Author: emgarten

build/config.props

@@ -13,8 +13,8 @@
     <AWSSDKSSOVersion>3.7.300.116</AWSSDKSSOVersion>
     <AWSSDKSSOOIDCVersion>3.7.302.27</AWSSDKSSOOIDCVersion>
     <DotNetConfigVersion>1.0.6</DotNetConfigVersion>
-    <AzureIdentityVersion>1.12.0</AzureIdentityVersion>
-  </PropertyGroup>
+    <AzureIdentityVersion>1.15.0</AzureIdentityVersion>
+  </PropertyGroup>
 
   <!-- Config -->
   <PropertyGroup>